1. Field of the Invention
The present invention relates to an interface unit for an electrophysiological measurement system of the type which allows electrical connections to be established between wires from catheter-mounted electrodes and a monitoring system in a variable manner, and in particular to a unit which includes a display for displaying a connection configuration.
2. Description of the Prior Art
Electrophysiological measurement systems generally include a monitoring system for one or more of receiving, storing, processing and displaying signals from a number of patient interactive elements such as catheter-mounted intracardiac electrodes, surface ECG electrodes, blood parameter sensors, and other physiological parameter sensors, and an interface unit. The monitoring system often includes a switching unit by which measurements may be selectively made using different combinations intracardiac electrodes.
The interface unit is typically disposed bedside to receive the proximal ends of wires which are connected at their distal ends to the patient interactive elements and to provide for their electrical connection to the switching unit of the monitoring system. The wires are received by the interface unit in releasable engagement with input terminals which, for the intracardiac electrodes, are often arranged at the outer surface of the unit in a grid fashion. An output socket is provided for electrical connection to the switching unit and has contacts, each of which is in fixed connection with a corresponding input terminal. Which electrode wire connects to which terminal is dependent largely on the combination of catheters being used for a particular physiological examination, the nature of that examination and how the monitoring system is configured to receive the electrical signals.
Before undertaking any physiological examination the system must be set-up so that the correct catheter wires are connected with the correct terminals on the interface unit. To facilitate this set-up it is known to provide an interface unit wherein each terminal is permanently labeled in numerical sequence for identification purposes. Each wire of a particular catheter is usually provided with an identifying label by the manufacturer. Look-up tables can be constructed using these two sets of labels to indicate the wire/terminal configuration required for a particular study. A wipe-clean surface may be available on the interface unit so that a non-permanent label can be provided for each terminal used in the examination which identifies the catheter electrode wire to be inserted according to the look-up table. Often during a physiology study, however, it is desirable either to move a catheter to a different measurement location, to alter the combination of catheters, or to re-define the measurement protocol for the same catheter combination. In any of these events, it is necessary to reconfigure the interface unit connections and in the process replace the particular labels on the interface unit to correspond with the new configuration. This can be tedious and time-consuming for the operator and may lead to an incorrect configuration being made during the two step process of identifying the correct look-up table and then transferring the tabulated assignments to visible labels on the interface unit.
To alleviate this problem it is known from U.S. Pat. No. 5,640,967 to provide an xe2x80x9cintelligentxe2x80x9d device which combines switching, amplification and interface functions in a single, compact bedside unit. A microprocessor controlled LCD screen display is provided to graphically display the connection configuration required for a particular measurement protocol. A memory also is provided for storing a library of different configurations for later retrieval and display.
With the additional electronic components this is relatively expensive to implement compared with the existing xe2x80x9cdumbxe2x80x9d interface unit in which essentially only the releasable connections between wires and terminals are selectively established (the connection between each terminal and a corresponding output pin of the unit remains fixed). Moreover, the use of an LCD display does not itself address the problem of the construction of readily interpretable labels.
An additional problem can result from the manufacturer""s normal practice of labeling the wires connecting each electrode of a particular catheter in numerical order, when trying to establish the correct electrode wire connection at the interface unit, since each catheter in a combination of catheters will contain identically identified wires. Labels in this circumstance cannot be easily constructed which provide for an intuitive (and thus inherently safer) correlation between wire and terminal.
An object of the present invention is to provide an interface unit wherein a library of wire/contact configurations can be established relatively inexpensively and without the addition of complex electronic components, thereby providing a unit in which the visual portrayal of wire/catheter combinations can be readily varied.
The above object is achieved in accordance with the principles of the present invention in an interface unit for an electrophysiological monitoring system having a plurality of electrical receptacles for respectively receiving individual wires for different channels of the monitoring system, each receptacle being releasably engageable with the individual wire, and a display at an exterior surface of the interface unit which provides a visual indication of a wire/receptacle configuration for each of the number of stored configurations. In one embodiment, the display is formed by a number of overlays which are individually and removably placeable at the exterior surface. Each overlay, on an overlay face thereof, carries a visible indication of a different one of the stored configurations.
In another embodiment, the receptacles are disposed in a grid on the exterior surface of the interface unit in different groups, and the display is permanently disposed at the exterior surface and provides a visual indication of each grouping of the receptacles.
Each overlay of the library may be retained on, and possibly movable over, binding posts which are attached to the housing of the interface unit. This arrangement helps maintain the integrity of the library and can aid the correlation of the overlay with the upper surface of the housing.
Preferably each overlay is constructed so that contacts for each catheter of a catheter combination are grouped together with the visible indication preferably including a visible demarcation, such as a lined or colored/shaded block demarcation or an interconnecting line demarcation, of the different groups of contacts; an identifier to visibly link an individual catheter to a particular contact grouping, for example a label or colour code identifier; and wire label identifiers which preferably correspond to the catheter manufacturer provided wire identifiers. In this manner a readily interpretable indication of the expected wire/contact configuration is provide in a single overlay without having to memorize or frequently record complex and abstract xe2x80x9cartificialxe2x80x9d label identifiers. This grouping and labeling arrangement also can be employed to similar advantage with other display types such as an LCD screen display or a permanently fixed display.